Refiner for fibre suspensions

ABSTRACT

A REFINER FOR FIBRE SUSPENSIONS COMPRISES A STATIONARY DISTRIBUTOR DRUM WITH AN INLET FOR FIBRE SUSPENSIONS AND A GRINDING APPARATUS SURROUNDING OUTLETS IN THE DISTRIBUTOR DRUM. THE GRINDING APPARATUS INCLUDES A PERFORATED, ROTATABLE, CYLINDRICAL WALLL SURROUNDED BY A PLURALITY OF PERFORATED, ARCUATE GRINDING PLATES SPACED AND SECURED AROUND THE PERIPHERY OF THE CYLINDRICAL WALL AND CONNECTED TOGETHER BY A LINKAGE COUPLED TO AN ADJUSTMENT DEVICE WHICH CAN CONTROL THE CLEARANCE BETWEEN THE GRINDING PLATES AND THE CYLINDRICAL WALL. EACH GRINDING PLATE EXTENDS OPPOSITE AN OUTLET OF THE DISTRIBUTOR DRUM AND A PORTION OF THE DRUM AHEAD OF THE OUTLET AS VIEWED IN THE DIRECTION OF ROTATION OF THE CYLINDRICAL WALL.

0d. 25, 1811 v, sso 3,615,08

REFINER FOR FIBRE SUSPENSIONS Filed July 3, 1969 15 v Fl .1 17 L0 9 v 39 1o 11 United States Patent 3,615,058 REFINER FOR FIBRE SUSPENSIONS Harry Vilhelm Nilsson, Vanersborg, Sweden, assrgnor to Aktiebolaget Vargons Mek. Verkstad, Vargon, Sweden Continuation-impart of application Ser. No. 662,653,

Aug. 23, 1967, This application July 3, 1969, Ser. No. 838,893 Claims priority, application Sweden, Sept. 30, 1966, 13,228/ 66 Int. Cl. B02c 17/02 U.S. Cl. 241-85 6 Claims ABSTRACT OF THE DISCLOSURE A refiner for fibre suspensions comprises a stationary distributor drum with an inlet for fibre suspensions and a grinding apparatus surrounding outlets in the distributor drum. The grinding apparatus includes a perforated, rotatable, cylindrical wall surrounded by a plurality of perforated, arcuate grinding plates spaced and secured around the periphery of the cylindrical wall and connected together by a linkage coupled to an adjustment device which can control the clearance between the grinding plates and the cylindrical wall. Each grinding plate extends opposite an outlet of the distributor drum and a portion of the drum ahead of the outlet as viewed in the direction of rotation of the cylindrical wall.

This application is a continuation-in-part of my earlier application Ser. No. 662,653 filed Aug. 23, 1967, and now abandoned.

The invention relates to a refiner or beater for fibre suspensions, such as pulp. The refiner is of a type comprising a perforated wall member movable about an axis and having on one side thereof perforated plates which are mounted stationarily to serve as grinding members in cooperation with the wall member surface. In the preferred embodiment the wall member is a cylinder and the grinding members are arcuate and are disposed on the outside of the cylinder.

In a known refiner of this type, arcuate, perforated plates are resiliently forced tightly against a stationary cylindrical wall formed with axial flutes, and inlets for the suspension are provided outside of the cylinder wall behind the grinding plates, as seen in the direction of rotation of the cylinder, whereby the refined pulp is caused to pass through the perforations of said plates. However, the apparatus has a rather limited capacity in spite of its great consumption of power, and, above all, it is difficult to control the degree of beating with accuracy.

The invention has for its purpose to provide a refiner or beater which is easy to adjust for obtaining a desired degree of beating, at the same time as a gentle treatment of the fibres is assured. In the new apparatus, the perforated wall has on the side opposite the grinding members a stationary distributor for suspension to be treated having a plurality of outlets spaced along the path of movement of the wall member to direct the outflow onto the side of the wall member opposite the grinding members. Further, the grinding members are adjustable to leave a desired clearance in relation to the wall member and each plate extends along at least a substantial part of the wall member portion opposite to an outlet from the distributor as well as a preceding wall portion, as seen in the direction of rotation of the cylinder. Thus, the suspension flows from the outlets of the stationary distributor through the perforations of the wall member and beyond said wall the fibres are concentrated and beaten during a continuous feed through the clearances between the wall member and the grinding plates. A refiner constructed in this way has a surprisingly great capacity in spite of a relatively low consumption of power, and for a given capacity the apparatus can thus be dimensioned considerably smaller than known refiners, so that the demand for room will be correspondingly reduced.

The new refiner and its function will be further described in the following with reference to the drawing in which:

FIG. 1 is an elevation view in axial section of a preferred embodiment, and

FIG. 2 is a transverse cross section through the same apparatus.

The apparatus shown is supported by a stand 10- in which a horizontal drive shaft 12 is journalled by means of roller bearings 13, 14. A pulley 11 secured to one end of the shaft (to the right in FIG. 1) is adapted tobe driven by a motor, not shown. At the left in FIG. 1, the stand 10 carries a cylindrical housing .15. An outer end wall 17 of said housing 15 has a central opening 17' adapted to be connected to a conduit (not shown) for supply of fibre suspension. At its top the housing has an outlet 16, which may also be connected to a conduit, not shown. If desired, the outlet may instead be directed to one side or downwards.

The end of the driving shaft 12 extends into the housing 15 and carries therein a grinding cylinder 26 consisting of a perforated, cylindrical wall 27 and a solid end wall 28. A heavy hub portion 28' provided centrally in said end wall 28 is keyed to the end of the shaft 12 and secured by a nut 29.

The cylinder wall 27 coaxially surrounds a cup-shaped drum 18 also inserted in the housing .15. The drum 18 has an open end fixed to the end wall 17 of the housing 15 to permit the interior of the drum to be in communication with the inlet 17'.

In the embodiment shown, the distributor drum 18 has three outlet openings 19 (FIG. 2) equally spaced around its periphery and extending axially along the major part of the inside of the cylinder wall 27. Each such opening 19 is bordered by two ribs 20, 21 formed on the exterior of the cylindrical wall of the drum 18. The ribs 20, 21 extend axially to serve as supports for sealing members or shoes 22 and 23, respectively, mounted thereon. As seen in FIG. 1, the supporting top surface of each rib 20- (or 21) and the supported surface of the associated sealing shoe 22 (or 23) are correspondingly wedge-shaped in the longitudinal direction, whereby a desired clearance between the shoes and the inner side of the cylinder wall 27 may be adjusted by displacing the shoes axially. For that purpose, the shoes 22, 23' may be secured by means of bolts 24 passing through oblong openings in the ribs 20, 21, but other adjustable fastening means are also utilizable. In the drawings, the shoes are shown in engagement with the cylinder wall 27, but in practice a clearance of at least several tenths of a mm. is generally provided.

The cylinder wall 27 of the rotary grinding cylinder is partly surrounded by three grinding members in the form of arcuate, perforated grinding plates 30 spaced around the periphery and extending axially along the cylinder wall with some clearance thereto. As will be described in detail in the following, the clearances form narrow passages 31 for material to be ground, and the width of said passages may be adjusted by means also described hereinafter. As seen in the cross section in FIG. 2, each plate 30 preferably covers at least the major part of the cylinder wall portion opposite an outlet 19 from the drum 18 as well as a preceding cylinder wall portion, as seen in the intended direction of rotation of the cylinder (indicated by an arrow in FIG. 2). Further, it may be noted that the perforations in the cylinder wall 27 are preferably a little larger than the perforations in the plates 30.

- Each plate 30 has a pair of connection lugs 32, 33 at each end, and the lugs 32 at one end of a plate are, by means of two parallel links 34 or 35, hingedly connected to the lugs 33 at the opposite end of another plate in such away that an open-ended chain is formed around the cylinder wall 27. (One link only in each pair of links appears from FIG. 2). The upper plate 30 to the right in F IG. 2 has its two upper lugs 33 hingedly connected to short links 36, which are pivotably mounted on a horizontal shaft 37 secured in the housing in a manner not shown. The upper lugs 32 on the plate to the left in FIG. 2 are connected to a yoke 38 formed integrally with a sleeve 39 in which a non-threaded end of a set screw 40 is rotatably secured in such a way that a swivel connection is formed. A threaded porion of the set screw 40 is screwed'through a nut 41, which is mounted in a guide sleeve 41' inserted through the wall of the housing 15, and the device is such that the screw extends substantially tangentially to the cylinder wall 27. In this connection it may be noted that the links 36 at the opposite end of the chain preferably extend in about the same direction as the screw 40. A hand wheel 42 is secured to the end of the screw 40 protruding outside the housing 15, and the screw may be locked in an adjusted position by means of a lock ing nut 44 provided with a grip 43. It is evident that the width of the clearances or passages 31 between the plates 30 and the cylinder wall 27 may be increased or decreased by turning the screw 40 in that the left-hand plate 30 in FIG. 2 is moved clockwise or counter clockwise, while the links 36 are swung a little around their pivot shaft 37. Of course, the width of the passages 31 is determined with regard to the desired degree of grinding. It is also evident that the invention is in no Way limited to the plate setting mechanism described above, but other mountings may be equally utilizable.

In the operation of the apparatus described, the shaft 12 may be driven at a speed of about 800 rpm, for example, and the fibre suspension to be beaten is supplied continuously through the inlet 17 at a pressure of 2 atm. gauge, for example. From the distributor drum 18 the suspension flows through the outlets 19 onto the rotating cylinder wall 27 and further radially outwards through the perforations of said wall into the passages 31. The finer and shorter fibres which must not be beaten, pass rather unimpededly through the perforations of the plates 30 together with a major proportion of the water. Contrary thereto, the longer and coarser, possibly lumped fibres are influenced outside the cylinder wall 27 by the speed of rotation of the cylinder in such a way that they are bent backwards, i.e. they are orientated more or less peripherally to extend crosswise to the perforations of the plates 30, whereby their discharge through said perforations is prevented. Consequently, the longer and coarser fibres are fed through the passages 31 in the direction of rotation of the cylinder wall 27 during a simultaneous and progressive dewatering and thickening of the pulp, and the fibres will thereby be beaten partly'against each other, partly against the cylinder wall and the inner surfaces of the plates 30. Owing to the concentration of the fibres between the grinding surfaces, a very effective grinding is obtained without any noticeable risk of shearing or cutting, as otherwise often occurs in known refiners. At the fore ends of the passages 31 (as seen in the direction of rotation) the thickened and beaten pulp is forced out to be mixed with the suspension within the surrounding portion of the housing 15, and the mixture is then discharged through the outlet 16.

It may be noted that in the embodiment shown in FIG. 2, the outlet openings 19 of the drum 18 are not completely covered by the plates .30. Hereby a portion of the water is permitted to escape together with finer fibres without being obstructed by the plates. On the other hand, the longer fibres have no time to be free from the perforations in the cylinder wall 27, before they are drawn into 4 the passages 31, and thus the sought grinding in no way imparied.

It is obvious that the illustrated preferred embodiment described above may be modified in several respects within the scope of the invention.

For example, the grinding members and their adjustment linkage may be located on the inside of the cylinder with the distributor outlets located outside the cylinder. [11 such case the treated suspension is removed from the insideof the cylinder. While such modification utilizes the novel principle of the invention it may be less desirable than the, preferred embodiment, among other reasons because it operates against rather than with the centrifugal force of the rotating cylinder and therefore requires more input pressure. Also, the perforated wall member need not be a cylinder but may be a perforated belt or screen movable over guides or rollers about a more or less central axis, or may be a disc rotatable about its center with the grinding members and distributor outlets located on opposite sides of the disc and the perforations in the disc and the grinding members extending axially of the disc or at an outward angle to the disc axis. Other modifications within the scope of the invention will be obvious to those skilled in the art.

What I claim is: I

1. A refiner for treating fibre suspensions, such as pulp, comprising a perforated wall member movable about an axis and having on one side thereof perforated grind ing members mounted stationarily and providing a grinding action in cooperation with the surface of the wall member, the wall member having at the side thereof opposite said grinding members a stationary distributor for suspension to be treated having a plurality of outlets spaced along the path of movement of said wall member to direct the outflow onto the adjacent side of the wall member, the grinding members being adjustable to leave a desired clearance in relation to the wall member, each grinding member extending along at least a substantial part of the portion of said wall member opposite to an outlet from the distributor as well as a preceding wall member portion, as seen in the direction of movement of said wall member.

2. A refiner as claimed in claim 1, in which the perforations of said wall member are larger than the perforations of said grinding members.

3. A refiner as claimed in claim 1, in which the outlets from said distributor are bordered by sealing shoes which are adjustable to leave a desired clearance in relation to the adjacent surface of said wall member.

4. A refiner as claimed in claim 1, in which said Wall member is a cylinder rotatable about the axis thereof.

5. A refiner as claimed in claim 4, in which the grinding members are arcuate and are located on the outside of said cylinder partially surrounding the axis thereof and the outlets of said distributor are located on the inside of said cylinder. 1

6. A refiner as claimed in claim 4, wherein the'grinding members are hingedly connected by links in the form of an open-ended chain extending in a loop about the axis of the cylinder, one end of said chain being secured by means of links carried by a stationary support, while the opposite end of the chain is connected to a setting member movable tangentially to the cylinder wall to make possible an adjustment of the Width of the passages between the cylinder wall and said grinding members.

action is References Cited UNITED STATES PATENTS 3,194,540 7/1965 Hager 24186 X ROBERT C. RIORDON, Primary Examiner G. L. SMITH, Assistant Examiner U.Sl Cl. X.R. 241-90, 9 1, 

